insertMany does not take nested/subdocument schema into account for timestamps

[eliw00d]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

6.1.5

Node.js version

16.13.0

MongoDB server version

4.4.12

Description

insertMany adds createdAt and updatedAt if timestamps: true for parent document but not for child document with the same settings.

It honors _id: false for both parent and child documents, so I would expect this is just a bug.

I did a search for existing issues and came across one but it seems no follow-up issue was ever created: #4155 (comment)

Steps to Reproduce

const mongoose = require('mongoose')
const { Schema } = mongoose

const childSchema = new Schema(
  {
    name: { type: String },
  },
  {
    _id: false, // honored
    timestamps: true, // not honored
  }
)

const parentSchema = new Schema(
  {
    child: {
      type: childSchema,
    },
  },
  {
    timestamps: true,
  }
)

const Test = mongoose.model('Test', parentSchema)

async function run() {
  await mongoose.connect('mongodb://localhost:27017')
  await mongoose.connection.dropDatabase();

  await Test.insertMany([{ child: { name: 'child' } }])

  console.log(await Test.find())
}

run()

Expected Behavior

I would have expected the nested/subdocument to also have its schema options of timestamps: true honored when inserting.